1. Field of the Invention
The present invention relates to a dynamo electric machine and a method of manufacturing the same, and, in particular, relates to a dynamo electric machine which is suitable for size reduction and a method of manufacturing the same.
2. Conventional Art
As, for example, disclosed in JP-A-10-66314 (1998), JP-A-8-298756 (1996) and JP(PCT)-A-10-507057 (1998), a stator winding of a conventional dynamo electric machine is constituted in such a manner that a plurality of unit windings are manufactured in advance by molding a winding conductor wound in a plurality of times in a predetermined shape (for example, a hexagonal shape) and are disposed into a plurality of slots in a stator core so that each of the unit windings crosses over the plurality of slots. Further, as disclosed in JP-A-6-209535 (1994), each of a plurality of unit windings which constitutes the stator winding is constituted by two parts one as an in-slot coil and the other as an inter slot crossover coil.
The above referred to crossing over amount of the unit winding is determined based on the number of poles of the stator, therefore, the length of the end section of the unit winding is determined by the magnitude of the crossing over amount. When the number of poles of the stator is large, the amount of crossing over of the unit winding generally decreases, therefore, the length of the end section of the unit winding is shortened in comparison with a stator having a small number of poles. Further, the length of the end section of the unit winding can be shortened by a certain degree by improving the shape of a portion corresponding to the end section of the unit winding of a winding frame used when winding the winding conductor.
However, when the length of the end section of the unit winding is greatly shortened, the disposing work of the winding conductor into slots of the stator core is disturbed. Therefore, the following measure is conceived, in that at the time of disposing the unit winding while limiting the length shortening of the end section of the unit winding so as not to disturb the disposing work, the unit windings are disposed into the slots of the stator core, and after completing the disposing of all of the unit windings the respective sections of the unit windings are forcedly shaped to shorten the same.
However, such manufacturing method requires a large mechanical force to shape the end sections of the unit windings, further, when shaping the end sections of the unit windings, such as an insulating member inserted in the slots of the stator core and an enamel insulative coating applied over the surface of the winding conductor may be damaged, which likely causes a lowering of the break down voltage of the stator and a decrease in the performance of the dynamo electric machine concerned. Still further, the amount of the forced shortening of the end sections of the unit winding is limited, therefore, it is impossible to expect a significant shortening of the end section of the unit winding with such measure.
With regard to the above problem, in the former prior art referred to above, it is impossible to shorten the length of the end section of the unit winding while preventing disturbance at the time of the disposing work of the winding conductor, because the unit windings are shaped in advance. Further, the latter prior art referred to above takes no account of the significant shortening of the length of the end sections by shaping the end sections of the unit windings.
An object of the present invention is to provide a size reduced dynamo electric machine by shortening the end section of the stator winding.
Another object of the present invention is to provide a method of manufacturing a dynamo electric machines which can shorten the end section of the stator winding.
Still another object of the present invention is to provide a dynamo electric machine of which an insulating property can be enhanced and a method of manufacturing the same.
A further object of the present invention is to provide a dynamo electric machine of which the cooling efficiency at the end section of the stator winding can be enhanced and a method of manufacturing the same.
One of the features of the present invention is that each of a plurality of unit windings constituting the stator winding is formed by dividing it into at least two winding sections. More specifically, each of a plurality of unit windings constituting the stator winding is formed by dividing into a first winding section of which one of end sections is opened, opposing side sections are shaped so as to form a step in the radial direction of the stator core, the open ends of the opened end section face each other in the radial direction of the stator core and the opened end section is bent in a crossing over direction of the unit winding, and a second winding section connecting the open ends of the first winding section.
Herein, the end sections of the unit winding imply portions in the unit winding which project from both end portions in the axial direction of the stator core to the outside in the axial direction of the stator core and are called sometimes as a coil end portion. The side sections of the unit winding imply portions in the unit winding which are disposed in the slots of the stator core and are called sometimes as a coil side portion.
In the present invention, the stator winding is constituted by disposing a plurality of unit windings in a plurality of slots in the stator core in such a manner that one of the two side sections of a unit winding is disposed in a slot other than a slot where the other side section of the unit winding is disposed while crossing over a plurality of slots. Namely, the stator winding is constituted by a so called distributed winding. In such instance, in the present invention, the stator winding is constituted by repeating the following process by the number of the unit windings.
The first winding section is formed in advance in such a manner that a plurality of winding conductors laminated in a straight shape are twisted at the midway area thereof so that the width between the two side sections thereof crosses over a plurality of slots, a step is formed between the two side sections in the radial direction of the stator core and straight shaped open ends are formed at one of two end sections. Subsequently, the two open ends of the first winding section are inserted into two slots from one side of both ends in the axial direction of the stator core. Then, the straight shaped open ends of the first winding section which is projected from the other side of both ends in the axial direction of the stator core are bent in the crossing over direction of the unit winding so that the open ends face each other in the radial direction of the stator core. Finally, the open ends of the opened end section of the first winding section are connected by a winding conductor piece constituting the second winding section.
When connecting the opened end section of the first winding section by a winding conductor piece constituting the second winding section, in order to form a winding conductor having a plurality of turns among at least two winding conductors constituting the first winding section one of the open ends of one winding conductor and the other open end of the other winding conductor are connected by fastening therebetween the winding conductor pieces constituting the second winding section and the same operation is performed depending on the number of winding conductors in the unit winding. The unit winding is constituted by forming from a lamination of a plurality of flat shaped winding conductors.
As a result, in each of the slots of the stator core, a plurality of unit windings are disposed in such a manner that unit windings having different crossing over directions are piled in a slot in its depth direction, the laminating direction of the winding conductors constituting a unit winding is in the latitudinal direction of the slot and a plurality of unit windings are disposed in a slot. At this instance, the respective opened end sections of the plurality of unit windings are formed in such a manner that two portions which project from an end in the axial direction of the stator core to the outside in the axial direction of the stator core are bent in the crossing over direction of the unit winding, the two portions bent in the crossing over direction of the unit winding are stepped in the radial direction of the stator core and twisted portions of the two portions bent in the crossing over direction of the unit winding are extended in the radial direction of the stator core. Further, the end sections at the opposite sides of the respective opened end sections of the plurality of the unit windings are shaped in advance when forming the first winding section so as to have the same shape as the opened end sections as explained.
According to the present invention, since the unit winding is divided into at least two winding sections, in that divided into the first winding section having the opened end sections and the second winding section for connecting the open ends of the opened end sections of the first winding section, a conventional restriction subjected when disposing a unit winding formed by winding the winding conductor in a plurality of turns (for example, in a hexagonal shape), namely, the restriction that the length of the end section of the unit winding has to be kept within a length which prevents interference between the unit windings, is freed.
Moreover, according to the present invention, since the unit winding is constituted in such a manner that the opened end sections of the first winding section of which opposing side sections are stepped in the radial direction of the stator core are bent in the crossing over direction of the unit winding so as to oppose the opened end sections each other in the radial direction of the stator core as well as the open ends of the opened end sections of the first winding section are connected by the winding conductor piece constituting the second winding section, at least the opened end sections of the unit windings are formed in such a manner that two portions which project from the end in the axial direction of the stator core to the outside in the axial direction of the stator core are bent in the crossing over direction of the unit winding, the two portions bent in the crossing over direction of the unit winding are stepped in the radial direction of the stator core and twisted portions of the two portions bent in the crossing over direction of the unit winding are extended in the radial direction of the stator core, thereby, the opened end section of the unit winding is shortened by the amount of the twisted portion of the two bent portions in the crossing over direction of the unit winding.
Accordingly, in the present invention, the length of the respective end sections of a plurality of unit windings can be greatly shortened. Further, since the end sections of the respective closed end sections of the plurality of unit windings are formed in the same shape as those of the opened end sections, the length of the respective end sections of the plurality of the unit windings can be further shortened.
Further, according to the present invention, when shaping the end sections of the first winding section disposed in the slots of the stator core in a predetermined shape, the shaping is performed under a condition that the end section of the first winding section is opened, therefore, no large mechanical force is required therefor, therefore, a possibility of damaging the insulating member inserted in the slots of the stator core and the insulative coating applied over the surface of the winding conductors is small.
Still further, according to the present invention, since the respective end sections of the plurality of the unit windings are formed and arranged orderly in such a manner that two portions which project from the end in the axial direction of the stator core to the outside in the axial direction of the stator core are bent in the crossing over direction of the unit winding, the two portions bent in the crossing over direction of the unit winding are stepped in the radial direction of the stator core and twisted portions of the two portions bent in the crossing over direction of the unit winding are extended in the radial direction of the stator core, a ventilation resistance to cooling wind can be reduced.